IN-VITRO MICROAUTORADIOGRAPHY OF ATRIAL-NATRIURETIC-PEPTIDE IN BIOPSYSPECIMENS FROM PATIENTS WITH RENAL DISEASES

We investigated the localization and density of atrial natriuretic pep tide (ANP) receptors in human renal biopsy specimens by using in vitro micro-autoradiography (ARG) of [I-125]-alpha-human (1-28) ANP. In a p reliminary study, we measured the effect of storing tissue samples on ANP binding, using in vitro micro-ARG of Wistar rat kidney under optim al conditions. Duration of the preservation period did not affect ANP binding to renal tissue until samples had been stored at -30-degrees-C for two years. A total of 11 human renal tissues were used to assay b inding of ANP-ARG, including normal tissue obtained after nephrectomy because of renal cancer. ANP binding occurred predominantly within the glomerulus and, to a lesser extent, in the tubular region both in rat kidney sections and in human renal biopsy specimens. The density of A NP binding, calculated by counting grains in fixed areas, was compared with normal and pathological tissues. The density of grains tended to decrease in patients with renal dysfunction and hypertension except f or one case of IgA nephropathy with normal renal function and blood pr essure. The density of grains increased in a patient with nephrogenic diabetes insipidus. In the present study, we have established a method that uses in vitro micro-ARG for assessing ANP binding in human biops y specimens.